Police have taken into custody a 14-year-old boy who is suspected of planning a "Columbine" type event at a Pennsylvania high school, a police spokesman said. Police in Plymouth Township near Philadelphia took the boy into custody after a search of his home turned up a number of weapons, including a 9 mm rifle with a laser scope and dozens of air guns, said Deputy Chief Joe Lawrence.Police also found an operational hand grenade, three other hand grenades in the process of construction, bomb-making equipment, manuals and 30 powered weapons that fire BBs. The boy's mother bought the rifle for him several weeks ago at a gun show, police said. No ammunition was found for the rifle. The grenades were made with plastic casings that authorities believe the boy bought on the Internet, Lawrence said. The operational hand grenades included black powder, BBs and a fuse believed used in fireworks. Lawrence said police are also investigating whether the boy's mother bought him black powder used in the grenades. The boy was making the grenades in his bedroom, he said.